For conventional applications using potential-free contacts, PhotoMOS or solid-state relays are often implemented. However, these relays may be too slow for some applications to the field or may require their own isolated power source. A standard field-effect transistor (FET) driver could be implemented as an alternative in some applications. However, standard FET drivers add direct current to the field. Therefore, for applications in which direct current cannot be added to the field, standard FET drivers cannot be used as an alternative to PhotoMOS or solid-state relays.